1. Technical Field of the Invention
The present invention relates to a transportation system for transporting objects before and after processing, for example, substrates for liquid crystal display (referred as "LCD substrates" hereinafter), semiconductor wafers, or the like, and also relates to a processing apparatus equipped with the transportation system for transporting the objects.
2. Description of the Related Art
As the processing apparatus of this kind, there has been widely employed a multi-chamber type of processing apparatus. The multi-chamber processing apparatus includes a plurality of processing chambers (e.g. three chambers) for applying identical or different kinds of treatments on the objects under atmosphere of reduced pressure, a transporting chamber having a function as a second load-lock chamber connected with the processing chambers, a load-lock chamber connected with the transporting chamber as well as the processing chambers and a mechanism for delivering the LCD substrates from a carrier mounted on a mounting mechanism to the load-lock chamber and vice versa.
In operation of the above apparatus, the substrate is brought into the load-lock chamber by the carrier. The substrate loaded in the load-lock chamber is transported from the load-lock chamber into a designated processing chamber by a transporting mechanism arranged in the transporting chamber. In the processing chamber, the substrate is subjected to a film deposition process by the plasma CVD method. Thereafter, the substrate upon completion of the film deposition process is accommodated in the carrier mounted on a second mounting mechanism, in the opposite course to the above course.
As the transporting mechanism, there has been employed an articulated robot which is provided, at a tip thereof, with a catch plate for mounting the substrate thereon. Recently, for the purpose of increasing the throughput, there is used a transporting mechanism having an upper catch plate and a lower catch plate in the "two-stage" arrangement. In the mechanism, one catch plate is used in order to load the substrate into the processing chamber, while the other catch plate is used to unload the substrate from the processing chamber. Two groups of substrate lifters (substrate supporting members) are arranged on a mounting table in the processing chamber. Each group of substrate lifters is adapted so as to move up and down in accordance with the designated steps.
Thus, in the processing chamber, the catch plates do not perform vertical movement in the processing chamber, and the lifters move up and down in accordance with predetermined steps so as to carry out the delivery of the substrates between the lifters and the catch plates. In this way, the operative cooperation of the catch plates in the two-stage arrangement with two groups of substrate lifters allows the loading/unloading of the substrates and the mounting/withdrawal on and from the mounting table to be performed effectively.
In the above-mentioned system, however, the control to drive the substrate lifters is apt to be complicated. Additionally, due to the complicated motion of the substrate lifters, there is an increased possibility that particles are produced in the processing chamber disadvantageously.